It would be foolish not to see hopeful signs in the conclusion of the Montreal climate talks this weekend. Any agreement backed by the Bush administration that is also hailed by green groups, including Friends of the Earth, clearly has something going for it. No concrete proposals were debated in Canada. None the less, it is significant that the United States, India and China - some of the world's main carbon dioxide producers - now seem prepared to talk about controlling their emissions beyond 2012, when the current Kyoto climate deals run out. If nothing else, it gives the world a platform on which to build better, more meaningful deals.

We should not let our optimism run out of control, however. For a start, any reduction in carbon dioxide emissions achieved by 2012 are destined to be painfully small. Each signatory nation has agreed to reduce emissions by 5.2 per cent of its 1990 output. But given that the US, the world's biggest emitter of carbon dioxide, as well as India and China, refused to sign up to Kyoto, there will be no halt in atmospheric change and little chance Earth will stop warming in that period.

In fact, our climate aspirations are still woefully inadequate. It is estimated mankind's industrial activities have already raised global temperatures by 1C, a rise that has triggered a 30 per cent reduction in the Gulf Stream's flow, melting of glaciers across the world and atmospheric instability everywhere. Yet that 1C heating is destined to treble unless we reduce current emissions by 60 per cent by 2050, say scientists. The Montreal agreement to talk about talks - once a few countries achieve a 5 per cent cut in emissions - is thin fare examined from this perspective.

On the other hand, it is clear the world is hardening in attitude to carbon emissions - even in the US. There, 192 cities and 10 states, including California and New York (both with Republican governors) have introduced curbs on greenhouse gases. And there are signs of similar changes in public perception in Europe and Asia. The world - thankfully - is slowly waking up to the danger of global warming. Whether it does so in time, is a different matter.